import math

x1, y1, x2, y2 = map(float, input().split())

dx = x1 - x2
dy = y1 - y2

d = math.hypot(dx, dy)

print(d) import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 dx = x1 - x2 dx x1 - x2 x1 x2 dy = y1 - y2 dy y1 - y2 y1 y2 d = math.hypot(dx, dy) d math.hypot(dx, dy) math.hypot math hypot dx dy print(d) print d x2, y2 = map(float, input().split()) map(float, input().split()) x2 dx = x1 - x2 x1 - x2 dx y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1 d = math.hypot(dx, dy) math.hypot(dx, dy) d y2 = map(float, input().split()) map(float, input().split()) y2 dy = y1 - y2 y1 - y2 dy x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1
import math

x1, y1, x2, y2 = map(float, input().split())

dx = x1 - x2
dy = y1 - y2

d = math.hypot(dx, dy)

print(d)